The present invention relates to a collapsible structure, such as a chair or stand, and more particularly to a collapsible structure characterized by a high level of stability and easily releaseable means for automatically locking it in the erected use orientation.
A wide variety of collapsible structures are well-known. Chairs and Z-stands are well-known examples in the furniture art. Such collapsible structures typically comprise first and second longitudinally extending rigid members, and means pivotally connecting the first and second members for movement between a compact storage orientation and an erected use orientation. In the compact storage orientation, the first and second members extend longitudinally in a substantially parallel relationship, both for ease of handling and for minimization of the storage space required. In the erected use orientation, the first and second members extend longitudinally in a substantially non-parallel relationship, so that the generally horizontal second member acts as a base or support for the generally vertical first member.
In some collapsible structures, there are first, second and third longitudinally extending rigid members. Adjacent one end of the first member (that is, the generally vertical member) first means are provided for pivotally connecting the first and second members for movement between a compact storage orientation and an erected use orientation. Adjacent the opposite end of the first member (that is, the generally vertical member) second means are provided for pivotally connecting the first and third members for movement between a compact storage orientation and an erected use orientation. In the compact storage orientation, the first, second and third members extend longitudinally in a substantially parallel relationship; and in the erected use orientation the second and third members extend longitudinally in a substantially non-parallel relationship with the first member, the second and third members typically extending longitudinally in a substantially parallel relationship with each other.
The known collapsible structures have not proven to be entirely satisfactory in use. First, in the erected use orientation the collapsible structures tend not to be as secure, reliable and rigid as counterpart non-collapsible structures. For example, a collapsible chair, typically has a different, often more wobbly, feel to a person sitting in the chair than a non-collapsible chair, and this difference can make the user feel somewhat insecure.
Second, typically the collapsible structure must be either automatically or manually locked into the erected use orientation. Manually locking of the collapsible structure is frequently awkward and time consuming. On the other hand, an automatic locking system must still be capable of manual release to permit subsequent movement of the structure into the compact storage orientation. However, commonly the manual release mechanism is either awkward and time-consuming to use or susceptible to being accidentally activated (for example, by the person sitting in the chair inadvertently activating the release mechanism) with unintended and potentially disastrous results.
Accordingly, it is an object of the present invention to provide a collapsible structure affording a very high degree of security when it is in the erected use orientation.
Another object is to provide such a structure which, in one preferred embodiment, automatically locks in the erected use orientation with the lock being protected against unintended release.
A further object is to provide such a collapsible structure which, in one preferred embodiment, combines a high level of security in the erected use orientation and protection against accidental release of the locking system.
It is also an object of the present invention to provide such a structure which is simple and inexpensive to construct, use and maintain.
It has now been found that the above and related objects of the present invention are obtained in a collapsible structure comprising first and second longitudinally extending rigid members and means pivotally connecting the first and second members for movement between a compact storage orientation, wherein said first and second members extend longitudinally in a substantially parallel relationship, and an erected use orientation, wherein said first and second members extend longitudinally in a substantially non-parallel relationship. Movement between the storage and use orientations requires movement of the second member through an arc greater than 180xc2x0 and less than 360xc2x0 into a reflex angle relative to the first member.
Preferably, the connecting means has one end thereof fixedly secured to the first member, extends transverse to the first member, and has an opposite end thereof pivotally secured to the second member. The connecting means limits movement of the second member through the arc beyond the reflex angle relative to the first member. The connecting means is configured and dimensioned to receive therein a full cross-section of the second member when the second member is at the reflex angle.
The present invention also encompasses a collapsible structure comprising first and second longitudinally extending rigid members, means pivotally connecting the first and second members for movement between a compact storage orientation wherein the first and second members extend longitudinally in a substantially parallel relationship and an erected use orientation where the first and second members extend longitudinally in a substantially non-parallel relationships. Locking means include a depressable locking button on the second member biased to extend outwardly therefrom, and an aperture in the first member configured and dimensioned to receive at least a portion of the button. A camming ledge extends outwardly from the first member and above the aperture both for automatically temporarily depressing the button as the second member moves from the storage orientation into the use orientation, and for limiting accidental depression of the button when the second member is in the use orientation and the button extends outwardly from the first member below the ledge, while still permitting intentional manual forcible depression of the button out of the aperture, thereby to enable movement of the second member from the use orientation to the storage orientation.
Preferably, the ledge extends outwardly from the first member at least as far as the portion of the button extending outwardly from the first member, is disposed closely adjacent the button portion, and extends upwardly and outwardly. The ledge may be a turned-out edge portion of the first member.
The present invention further encompasses a collapsible structure comprising first, second and third longitudinally extending rigid members. Adjacent one end of the first member, means pivotally connect the third and first members for movement between a compact storage orientation, wherein the third and first members extend longitudinally in a substantially parallel relationship, and an erected use orientation, wherein the third and first members extend longitudinally in a substantially non-parallel relationship. Movement between the storage and use orientations requires movement of the third member through an arc greater than 180xc2x0 and less than 360xc2x0xe2x80x94preferably an arc of about 280xc2x0xe2x80x94into a reflex angle relative to the first member.
Preferably, the connecting means has one end thereof fixedly secured to the first member, extends transverse to the first member in an opposed second direction, and has an opposite end thereof pivotally secured to the third member. In the storage orientations the first, second, and third members are substantially parallel, and in the use orientations the second and third members project to opposite sides of the first member.